fix(desktop): extract ObserverFn type alias to appease clippy::type_complexity

The thread_local OBSERVER field had an inline complex type that triggered
-D clippy::type_complexity on the push hook. Extract it to a type alias.

Co-authored-by: Will Pfleger <pfleger.will@gmail.com>
Signed-off-by: Will Pfleger <pfleger.will@gmail.com>

desktop/src-tauri/src/commands/identity_archive/mod.rs

@@ -360,8 +360,10 @@ pub(crate) async fn scoped_archive_operation(
 pub(crate) mod test_hooks {
     use std::{cell::RefCell, sync::Arc};
 
+    type ObserverFn = Arc<dyn Fn(&nostr::Event) + Send + Sync>;
+
     thread_local! {
-        static OBSERVER: RefCell<Option<Arc<dyn Fn(&nostr::Event) + Send + Sync>>> =
+        static OBSERVER: RefCell<Option<ObserverFn>> =
             const { RefCell::new(None) };
         static ATTEMPT_COUNT: RefCell<u32> = const { RefCell::new(0) };
     }